Brewster's angle describes the incident angle of light on a media boundary where the reflected ray is plane polarized. This angle is equal to arctan (n) where n is the refractive index of the second medium (assuming the first medium is air). The reason for this phenomena has to do with how electric dipoles in the media boundary absorb and emit incident light. For more on this go to wikipedia
What is polaroid film? How does a polaroid filter polarize incident light? extension material (from wikipedia polaroid) "The original material, patented in 1929 (U.S. Patent 1,918,848) and further developed in 1932 by//Edwin H. Land//, consists of many microscopic//crystals//of iodo//quinine//sulfate (//herapathite//) embedded in a transparent//nitrocellulose////polymer//film. The needle-like crystals are aligned during manufacture of the film by stretching or by applying electric or magnetic fields. With the crystals aligned, the sheet is//dichroic//: it tends to absorb light which is polarised parallel to the direction of the crystal alignment, but transmits light which is polarised perpendicular to it. The resultant electric field of an electromagnetic wave (such as light) determines its polarisation. If the wave interacts with a line of crystals as in a sheet of polaroid, any varying electric field in the direction parallel to the line of the crystals will cause a current to flow along this line. The electrons moving in this current will collide with other particles and re-emit the light backwards and forwards. This will cancel the incident wave causing little or no transmission through the sheet. The component of the electric field perpendicular to the line of crystals however can cause only small movements in the electrons as they can't move very much from side to side. This means there will be little change in the perpendicular component of the field leading to transmission of the part of the light wave polarized perpendicular to the crystals only, hence allowing the material to be used as a light//polariser//."
Just for fun, circular polarization (for source and explanation see UPenn lecture notes)
IB Physics Objectives
11.5.1 - Describe what is meant by polarized light.
Polarization is light then is only in one plane.
11.5.2 - Describe polarization by reflection.
(This may be illustrated using light or microwaves. The use of polarized sunglasses should be included.)
Light becomes polarized when it is reflected. Depending on the angle, light is polarized 100% or not at all.
When n2 is the refractive index of the material the wave is being reflected on, and n1 is the refractive index of the material the wave is traveling in.
11.5.4 - Explain the terms polarizer and analyser.
A polarizer is a material that creates polarized light, and an analyzer is a device that can tell you if light is polarized.
11.5.5 - Calculate the intensity of a transmitted beam of polarized light using Malus’ law.
Use Malus' Law to find the intensity of polarized light:
11.5.6 - Describe what is meant by an optically active substance.
(Students should be aware that such substances rotate the plane of polarization.)
An optically active substance is one that can change the plane of polarization. (Rotate polarized light, if you will.)
11.5.7 - Describe the use of polarization in the determination of the concentration of certain solutions.
If polarized light is put through an optically active solution, the concentration of the solution can be determined from the amount that the light is rotated.
11.5.8 - Outline qualitatively how polarization may be used in stress analysis.
Some materials become optically active when put under stress. By placing the stressed sample between a polarizer and an analyzer, the degree of stress can be determined.
11.5.9 - Outline qualitatively the action of liquid-crystal displays (LCDs).
(Aim 8: The use of LCD screens in a wide variety of different applications/devices can be mentioned.)
Wikipedia has an excellent diagram for this, so I'll point you there. The explanation will tell you more about LCDs then you ever wanted to know.
Diagram from http://micro.magnet.fsu.edu/primer/java/polarizedlight/brewster/brewsterjavafigure1.jpg
What is polaroid film? How does a polaroid filter polarize incident light? extension material (from wikipedia polaroid)
"The original material, patented in 1929 (U.S. Patent 1,918,848 ) and further developed in 1932 by //Edwin H. Land//, consists of many microscopic //crystals// of iodo//quinine// sulfate (//herapathite//) embedded in a transparent //nitrocellulose// //polymer// film. The needle-like crystals are aligned during manufacture of the film by stretching or by applying electric or magnetic fields. With the crystals aligned, the sheet is //dichroic//: it tends to absorb light which is polarised parallel to the direction of the crystal alignment, but transmits light which is polarised perpendicular to it. The resultant electric field of an electromagnetic wave (such as light) determines its polarisation. If the wave interacts with a line of crystals as in a sheet of polaroid, any varying electric field in the direction parallel to the line of the crystals will cause a current to flow along this line. The electrons moving in this current will collide with other particles and re-emit the light backwards and forwards. This will cancel the incident wave causing little or no transmission through the sheet. The component of the electric field perpendicular to the line of crystals however can cause only small movements in the electrons as they can't move very much from side to side. This means there will be little change in the perpendicular component of the field leading to transmission of the part of the light wave polarized perpendicular to the crystals only, hence allowing the material to be used as a light //polariser//."
Just for fun, circular polarization (for source and explanation see UPenn lecture notes)
IB Physics Objectives
11.5.1 - Describe what is meant by polarized light.
Polarization is light then is only in one plane.11.5.2 - Describe polarization by reflection.
(This may be illustrated using light or microwaves. The use of polarized sunglasses should be included.)
Light becomes polarized when it is reflected. Depending on the angle, light is polarized 100% or not at all.11.5.3 - State and apply Brewster’s law.
Brewster's Law (see http://hyperphysics.phy-astr.gsu.edu/Hbase/phyopt/polref.html for a small demo) gives you the angle at which light will be 100% polarized:When n2 is the refractive index of the material the wave is being reflected on, and n1 is the refractive index of the material the wave is traveling in.
11.5.4 - Explain the terms polarizer and analyser.
A polarizer is a material that creates polarized light, and an analyzer is a device that can tell you if light is polarized.11.5.5 - Calculate the intensity of a transmitted beam of polarized light using Malus’ law.
Use Malus' Law to find the intensity of polarized light:11.5.6 - Describe what is meant by an optically active substance.
(Students should be aware that such substances rotate the plane of polarization.)
An optically active substance is one that can change the plane of polarization. (Rotate polarized light, if you will.)11.5.7 - Describe the use of polarization in the determination of the concentration of certain solutions.
If polarized light is put through an optically active solution, the concentration of the solution can be determined from the amount that the light is rotated.11.5.8 - Outline qualitatively how polarization may be used in stress analysis.
Some materials become optically active when put under stress. By placing the stressed sample between a polarizer and an analyzer, the degree of stress can be determined.11.5.9 - Outline qualitatively the action of liquid-crystal displays (LCDs).
(Aim 8: The use of LCD screens in a wide variety of different applications/devices can be mentioned.)
Wikipedia has an excellent diagram for this, so I'll point you there. The explanation will tell you more about LCDs then you ever wanted to know.